Oil tank



Patented Apr. 17, 1928.

UNITED STATES PATENT JOSEPH N'r-MW, JR., F ARDMOBE, PENNSYLVANIA, ASSIGNOR '10 SIJ'N OIL COM- PANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

on. :rAnx.

Application filed June 8,

In tanks containing petroleum and its distillates, particularly gasoline and light crude oil, serious losses occur through breathing, which is caused by the formation and condensation of gas. It is known to provide means that allow'gas to breathe to and from one or more tanks through a pipe line, from and to a breather bag or balloon, which is located in a waterproof but not gas-ti ht) housing or enclosure entirely separate from the tank or tanks. In the daytime, due to the higher temperature and to the direct sunlight to which the tankis exposed, there is generation of vapor with breathingfrom thetank to the balloon, with resultant distension of the latter. At night, with reduction of temperature, there is condensation of gas, with resultant .breathing from the balloon to the tank, with resultant collapse of the balloon. It is obvious that, in order to make provision for extreme conditions of evaporation and condensation, the bag must be half full of gas under mean or average conditions. The bag, therefore, must beof such size and capacity that it cannot burst from over-inflation, and also that during deflation it will contain suflicient gas to draw on until it reaches the point of maximum possible deflation. Otherwise a vacuum will be produced with danger of collapse of the tank top. Experience has shown that the volume of the balloon should not be less than twenty-five per cent of the vaporvolume in the tank or tanks when the latter are filled to the usual point.

It must also be borne in mind that where the balloon is connected witha work-tank, that is, a tank from which oil is pumped, the .balloon must be made of relatively great capacity, so that it will be half full when the level of oil in the tank is mean or average and when the amount of vapor in the system is mean or average.v

The above described system involves, therefore, the use of a large and therefore expensive balloon and considerable expense in construction.

The object of my invention is-to provide means to produce expansible and contractible vapor space within, or communicating with the space above the liquid level of, the tank, without the utilization of a balloon, but which will have the same efiiciency as a balloon. In the preferred embodiment of my invention, I provide a expansible and col- 1926. Serial 110. 114,417.

lapsible diaphragm or bellows which, like a balloon, is freel expansible and contractible, but which may e made out'of half the material required to make a bag or balloon of the customary type and still have the capacity of accommodating itself to the maximum conditions of evaporation and condensation. A further feature of my invention, in its preferred form, is the provision of an expansible and collapsible diaphragm which may be distensible in one direction due to increase in I the pressure of gas above average and which may bedistensible in the other direction due to decrease in the pressure of gas below the average. This last named capacity is of especial importance when the device is applied to a work-tank. A further feature of my invention, when embodied in its preferred form, is the application of the diaphragm to the tank itself in such manner as to save a substantial part of the cost of constructing a separate building and pipe connections thereto.

In the accompanying drawing, which illustrates an embodiment of my invention in a preferredform,thefigure is a sectional elevational view.

The oil'tank comprises a bottom a, a roof I), a cylindrical wall d, and internal steel supporting columns 0. The construction/ of wall d may be the same as that of any ordinary oil.tank, as, for. example, sections of iron, steel or concrete, welded or riveted together. m is a vacuum relief valve and n a pressure relief valve. The roof I) overlies only that part of the tank outside the supporting columns 0. Supported 0n the roof, over'the center of the tank, is a housing 6, which should be water-tight: Arcuate angle irons 0 secure together columns 0 and roof 1),; similar angle irons p securehousing e to roof 6 and similar angle irons rsecure together the upright and lateral members of housing 6. Secured to the inner circular edge of the roof I; is a ring 7", to which is clamped the rim or edge of a diaphragm g. This diaphragm, when distended, as shown in the drawings, assumes the shape of a halfsphere, if its marginal contour is that of a circle, which contour it will have if the internal edge of the roof I) is circular, which shape will be most convenient when the invention is applied direct to the tank. It is 'not essential, however, that the opening Suitable means should be provided to counterbalance the weight of the diaphragm, as, for example, a counterweight it connected to the central portion of the diaphragm bymeans of a flexibleconnection i extending over idler pulleys 7' supported on the frame 3. Flexible connection '11 may be either a chain, rope, orwire and may-be secured to the diaphragm in any way in which it is customary to secure cords to gas bags.

When, due to the formation of gas, the tank breathes outward, usually during the daytime, the diaphragm is distended and occupies the position shown in the drawing. When the gas condenses and the tank breathes inward, usuallyat night, the diaphragm collapses and tends to distend in the opposite direction.

It is obvious that-the diaphragm may be of such size that, with a maximum cvaporation of vapor, it will he distended to the full-line position shown in the drawing, and that with a condition of maximum condensation, itwill distend to or toward the dotted line position 9 shown in the drawing. It is, however, desirable to prevent the diaphragm bulging downward to such an extent as to reach the level of liquid in the tank. This is prevented by the counterbalancing of the diaphragm by means of the weight I), although it does not prevent the diaphragm from beingcomplctely drawn' down and dis- I tended into the shape and position shown in dotted lines under a slight vacuum such as .that produced by pumping out the liquid expensive. It is clear, too, that the applica-' tion of a housing to the top of the tank involves an independent substantial saving 1n cost of construction, although my invention is not confined to a housing so positioned,

which might be impracticable if'it were desired to connect a single breather apparatus with a plurality of tanks,

A modification of my broad invention is disclosed in an application'tiledby me of even date herewith, Serial No. 114,418 and therein specifically claimed.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is: l

1. Means adapted to store oil and allow breathing due to formation and condensation of gas which comprises a tank of relatively large volume adapted to contain the oil, a. flexible diaphragm having a. substantially semi-spherical shape when distended and when distended having a volume that is small relative to that of the tank, means supporting the periphery of the diaphragm and so positioning the diaphragn'i as to subject it to oil vapor pressure on one side and atmospheric pressure on the other side, said diaphragm being therefore distensible in one direction away from a. plane intersecting its peripheralsupport upon accumulation of vapor and increaselof vapor pressure and being distensihle in the otherdirection upon condensation of vapor and decrease of vapor pressure.

2. Means adapted to store oil and allow breathing due to formation and condensation of oil vapor, con'lprising a tank having a rigid roof of annular shape enclosing a central opening, and a gas receiver and d1s-' placer consisting of a flexible diaphragm closing said opening and having a substantially semi-spherical form when distended to its fullest capacity, said diaphragm being exposed to oil vapor pressure within and to atmospheric pressure without and being dis tensible outwardly upon accumulation of vapor and increase of vapor pressure and distensible inwardly upon condensation of m por and decrease of vapor pressure.

In testimony of which invention, I have hereunto set my hand, at Philadelphia, Pennsylvania, on this 7th day of June, 1926.

' J. N. PEW, JR. 

